Hi Wang, (2014/07/01 15:46), Wang Shilong wrote: > Hi Satoru and all, > > I think there maybe a leftover issue. > That is if we don't set label, in default it will output a blank line. > > Steps to reproduce: > > # mkfs.btrfs -f /dev/sdb > # mount /dev/sdb > # cat /sys/fs/btrfs/<uuid>/label -->an extra line will be outputed. > > This is because in btrfs_label_show(), we did something like this directly: > > return snprintf(buf, PAGE_SIZE, "%s\n", fs_info->super_copy->label); > > Maybe we can have a check whether label is NULL before we output? > otherwise,the > extra blank line is outputed, IMO this is not so nice thing!
OK, how about it is? I also add a test for empty-label case. From: Anand Jain <[email protected]> generally if you use echo "test" > /sys/fs/btrfs/<fsid>/label it would introduce return char at the end and it can not be part of the label. The correct command is echo -n "test" > /sys/fs/btrfs/<fsid>/label This patch will check for this user error reproducer.sh: =============================================================================== #!/bin/bash TEST_DEV=/dev/vdb TEST_DIR=/home/sat/mnt umount /home/sat/mnt mkfs.btrfs -f $TEST_DEV UUID=$(btrfs fi show $TEST_DEV | head -1 | sed -e 's/.*uuid: \([-0-9a-z]*\)$/\1/') mount $TEST_DEV $TEST_DIR LABELFILE=/sys/fs/btrfs/$UUID/label echo "Test for empty label..." >&2 LINES="$(cat $LABELFILE | wc -l | awk '{print $1}')" RET=0 if [ $LINES -eq 0 ] ; then echo '[PASS] Trailing \n is removed correctly.' >&2 else echo '[FAIL] Trailing \n still exists.' >&2 RET=1 fi echo "Test for non-empty label..." >&2 echo testlabel >$LABELFILE LINES="$(cat $LABELFILE | wc -l | awk '{print $1}')" if [ $LINES -eq 1 ] ; then echo '[PASS] Trailing \n is removed correctly.' >&2 else echo '[FAIL] Trailing \n still exists.' >&2 RET=1 fi exit $RET =============================================================================== Signed-off-by: Anand Jain <[email protected]> Signed-off-by: Satoru Takeuchi <[email protected]> Reviewed-by: Satoru Takeuchi <[email protected]> Tested-by: Satoru Takeuchi <[email protected]> --- v6: fix empty-label case v5: tweak to be able to apply on the top of 402a0f4. add test program. v4: used memcpy and memset. Thanks David again v3: accepts review comments. Thanks David and Eric again v2: accepts review comments. Thanks Eric and Roman --- fs/btrfs/sysfs.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index df39458..68d1f63 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -363,7 +363,8 @@ static ssize_t btrfs_label_show(struct kobject *kobj, struct kobj_attribute *a, char *buf) { struct btrfs_fs_info *fs_info = to_fs_info(kobj); - return snprintf(buf, PAGE_SIZE, "%s\n", fs_info->super_copy->label); + char *label = fs_info->super_copy->label; + return snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label); } static ssize_t btrfs_label_store(struct kobject *kobj, @@ -374,8 +375,15 @@ static ssize_t btrfs_label_store(struct kobject *kobj, struct btrfs_trans_handle *trans; struct btrfs_root *root = fs_info->fs_root; int ret; + size_t p_len; - if (len >= BTRFS_LABEL_SIZE) + /* + * p_len is the len until the first occurrence of either + * '\n' or '\0' + */ + p_len = strcspn(buf, "\n"); + + if (p_len >= BTRFS_LABEL_SIZE) return -EINVAL; trans = btrfs_start_transaction(root, 0); @@ -383,7 +391,8 @@ static ssize_t btrfs_label_store(struct kobject *kobj, return PTR_ERR(trans); spin_lock(&root->fs_info->super_lock); - strcpy(fs_info->super_copy->label, buf); + memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE); + memcpy(fs_info->super_copy->label, buf, p_len); spin_unlock(&root->fs_info->super_lock); ret = btrfs_commit_transaction(trans, root); -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
